Airplane



Filed Oct. 23, 1930 3 Sheets-Sheet 2 INVENTOR.

l/l/ 'lll/ll ATTO RNEY

Feb. 14, 1933. A. QHLQEDDING AIRPLANE 3 Sheets-Sheet 3.

Filed Oct. 23, 1930 Si? 'K w/ INVENTOR.

Patented Feb. 14, 1933 UNITED STATES PATENT OFFlC ALFREiD C. LOEDDING, 0F BADEN, PENHSYLVANA, .ASSIGNOR 0F ONEl-FGUBTE T FRANK C. SGHROEDER, OF SEWICKLEY, PENNSYLVAN'IA ALRPLANE Application filed October 23, 1980. Serial No. 490,602.

l0 iiight of the airplane, due primarily to the construction o and/or the design of the auxiliary airfoil or airoils and the location or position of the said airfoil or airfoils relatively to the main wing or airioil or airtoils 15 o the airplane.

The present invention contemplates a construction embodying means to effectively increase the lifting force and etciency per unit of main wing area, and particularly for sinall- 29 angles of incidence of the flight of the air plane, whereby the. main airfoil area may be materially reduced to carry greater loads than heretofore, and Without increasing the niotor power; the said construction further E5 enables slower landing speeds than heretorore.

Among the objects oi the present invention are, to provide in an airplane an auxiliary cainbered airfoil having the curvature of its 30` upper and lower cambers generated on or from the curvature of the leading upper canibei of the main airfoil of the airplane, said upper and lower curvatures being direct functions thereof; to provide an airoil charu acterized in that the curvaturcoiZ its upper camber'is substantially the same as the curva,- ture of the leadingupper camber ofthe main airfoil; to provide an auxiliary airioil spaced 3 from the leading portion of the main airfoil and i adjustable with respect thereto by a movement thereof in a direction p-erpendicular to its aerodynamic chord; and to position the auxiliary airioil above and lspaced from 45 the main airfoil, to provide an air passage or slot therebetween, said auxiliary airfoil being positioned so as not to inask the leading portion oft' the main airfoil.

Additional objects and advantages will 53 become apparent from the following descrip tion taken in connection with the accompany ing drawings, wherein;

Fig. l is a plan view of an airplane, showing my invention embodied therein;

Fig. 2, a side elevation thereof;

Fig. 3, an enlarged detail section view taken onrthe line lilllll of Fig. l,'particularly showing'the adjustable mounting auxiliary airfoil;

Fig. il, a section taken on line liv-TV oil Fig. 3; and

Fig. 5, a diagrammatic view illustrating the steps in the method of designing my auxiliary airoil.

Referring to the drawings, 2 designates generally an airplane of the inonoplane type, having a' pair oi main airlf'oils or wings 8, fuselage Il, andan empennage 5 or the and well known construction. The airioils are preferably designed in the ,conventional Adjustably mounted and positioned adfa-1 cent the leading portion or nose 6 o each ci c the main airioils 3 and spaced therefrom, auxiliary airfoils A, the said auxiliary airfoils preferably extending substantially the length of the main airfoils.

One oi the important features oi my invention resides in the configuration oit the auxiliary air-foil or airfoils and the method or manner ot designing the auxiliary airioil section. As above stated, the main airfoil is formed from any standard airoil section; such a section, for example, is shown by the hatched linesof Fig 5 and .is generally designated b. The said section b is determined by an upper camber or curve 7, a lower cainloer or curve 8, a leading edge 9, and a trailing edge l0. The aerodynamic chord @if said section,'oi' the line joining the leading and trailing edges, is designated at ll.

The manner or method followed by ine in designing or producin r the desired auxiliary airfoil section is particularly shown in the dia rammatic view of Fig. 5. As indicated at l) therein, the standard airicoil section is inoved upwardly parallelto its aerodynamic chord 1l, through any desired distance after which it is moved forwardly along a .continuation of said chord for an ual distance. This position of the section determines a rtion 7a of the lower camber of the auxiliary airfoil section a, the said camber portion being definedby the leading portion o the upper camber 7 of the main or standard section b.

Then the section is moved forwardly 10 along the said continuation of its chord in the above displaced osition until the upper camber or curve 7 oi) the section b intersects the auxiliary section lower camber line 7a at 12, the said point of intersection being at or about the point of maximum ordinate of the upper camber ofthe standard section b, that is to say, the maximum ordinate with res ect to the aerodynamic chord 11. The lea ing portion o the upper camber 7 of the standard' section b in this position will deine the upper camber 7 b of the auxiliary section a, as clearly shown in part 2) of Fig. 5.

in the final ste (3) of ig. 5 the section E the position $2) is inverted and rotated about the point of intersection of its leading edge 9 and its aerodynamic chord 11, until leading portion oi the upper curve or carnber 7 thereof becomes tangent to the lower caraber ortion 7a; as determined in part (l), there y defining the lower caruber or curve portion of the auxiliary section a to complete the same.

Thus, it will be seen that the aum'liary airfoil section a is Jformed of a lurality of curves or embers comprising unctions or portions of a curve or camber of the .main .airioil section and more specically, the carnicero ci the said' section a are all defined by the leading portion oi the upper curve or fig somber 7 of the section b. lt will be understood that the method or manner of design- L ing, according -to my invention, may be vatied within the shill of the designer. For example, the point o intersection l2 or the catcher portion 7o and the camber 75 may be varied to alter the width of the resultant enmiiary airtoil section a.

llt should further be understood that my uren-tion contemplates an auxiliary cainbered i embodying a construction having the restare oi its upper camber substantially :are saine as the curvature of the leading upohsinber or" the main airfoih regardless the method followed 'in producing the said einwature, and that this applies also to the manner or producing the curvature of lower camber of the auxiliary airi'oil. The said section a, completed as shown in part {3} of Fig. 5, will be disposed in such. a 42 manner that its aerodynamic chord ila', te inclined at an angle of incidence c with respect to the aerodynamic chord di ci' renin airfoil section Also due to the man ci? defining the portion 7o of the 1 86 amber o the section o from the leading 'described' 'may tion of the uper camber 7 of the main section b, in displaced relationship, the intervening space between the said cambers decreases in height rearwardly of the sections, thereby forming a Venturi passage therebetween.

Hence, by constructing the auxiliary airfoil A of a uniform section a, and positionlng the said airfoil along the leading p0rt1on or nose 6 of a main airfoil or wing 3 havzng a uniform section b, in such a manner `that the plane of the aerodynamic chords 11a of the auxiliary airfoil A is inclined at an angle o with respect to the plane of the aerod namic chords 11 oi the main airfoil, the

enturi passage will form a Venturi slot 13 extendino' longitudinally oi the wing structure. When so positioned, it will be seen that' if the auxiliary air'foil A is moved in a direction perpendicular to the plane of its aerod namic chords 11a, the character of the enturi slot 13 will be maintained, and the auxiliary airfoil A will have a constant angle of incidence c with respect to the main airoil 3.

lt is also to be noted that when the section a is designed in the manner of my invention, the leading edge portion or nose 14 thereof is decidedly above and forward of the nose 6 of the main airfoil section b, so that when the wing assembly is made as above, the nose of the auxiliary airfoil A will not mask the nose 6 of the mafn airfoil 3. Thus, when the air lane 2 is in the normal flying position of 4ig. 2, o r when the angle of incidence of the airplane is zero, the wind may enter the Venturi. slot 13 between the auxiliary and the main airfoils. The passage of the wt'nd therethrough will increase the velocity thereof, and at the same time be caused to follow the u per camber 7 of the main airfoil rearwar ly to increase the lift.

lt has been found that the increased lift thus obtained is sutlicient to permit a reduction in the conventional wing area. of the main airfol (indicated in the dotted lines of Figs. 1 and 2) as much as 40 percent. Also, this reduction in area may be eli'ected without altering the landing speed and without increasing the motor power, and results in increased erformance and maneuverabilty of the airp ane.

As the airplane climbs with an increased angle of incidence, the volume of the air passing'through the Venturi slot 13 will be increased', thereby increasing'the resultant lift. This increased lift is accomplished with comparatively small values of the angle of incidence of the airiolane.

In the practice of my invention` the auxiliary airfoils A may be constructed in any desired manner; for example, a metallic coverin'g formed .into the design herenbefore be secured to suitable spars l5 and trailing edge members 16. The auxiliary airfoils may be mounted on the main airfoils by means of a plurality of spacedapart streamline supports, generally designated 17.

Some value of the height of the Venturi slot 13 will roduce a condition of maximum elliciency with an increased lift. Thereore, the auxiliary airfoil A may be so positioned as to normally provide this condition of maximum eiliciency, and suitable adjusting means may be rovided within the control of the aviator or varying the height of the slot 13 to provide flexibility of operation of the airplane. .a

To this end,I have shown in Figs. 3 and 4 a preferred construction of the said means for adjustably mounting the auxiliary airfoils A on the said supports 17, which may be of hollow construction. Each of the main airfoils 3 are provided with a longitudinally extending forward spar 18 and a nose cap 19, preferably formed of wood. Immediately below the said supports are transverse bulkheads 20 secured to the spar 18 and the nose cap 19.

Extending upwardly from the upper camber 7 of the main wing 3 and forming a part of the supports 17 are provided parallel guides 2l, securely fastened to the said spar and nose cap. The said guides are preferably disposedat .right angles to the plane of the auxiliary airfoil section chords 11a. Bearing rollers 22 are rotatably disposed in suitable recesses in the inner faces of the guides. Spaced-apart metallic ribs 23 are secured to the spar members of the auxiliary airfo'l A and are provided with depending portions 24 extending downwardly between v the guides 21, the said depending portions having bearing faces 25 for the rollers 22.

Centrally secured to the lowermost portion of each of the depending rib portions 24, I provide an adjusting screw 26 adapted to be translated along an axis perpendicular to the plane of the auxiliary airioil section chords 11a, by means of a threaded sleeve 27 rotatable in suitable bearings 28 mounted on the bulkhead 20. The said screw, sleeve and bearings are disposed within the main airfoil structure and forwardly of the forward spar 18 thereof.. A spur gear or worm wheel 29 is preferably formed integrally with the sleeve 27. l To enable the adjustment of the screws 26 of each support 17 in unison, I provide a transverse torque tube 30 extending substan tially the length of the auxiliar airfoils 3, as in Fig. l, and through the fuseage 4. The Said tube may be rotatably supported in the fuselage and in a plurality of spaced-apart bearings 31 secured to the forward spars 18 jef the-main wings 3. Spaced-apart worms '32 are secured to the tube 30 and are arranged in mesh with the gears 29 at each support 17 Thus, by rotating the torque tube 30, the auxiliary airfoils A may be adjusted to and from the leadin portions of the main airioils inthe manner escribed. This may be done from the coclopit 33 by the aviator, through the medium of sprockets 34 and a connecting chain 35.

A metallic or other covering 36 may be placed around the supports 17 to aord a streamline edect for reducing the air resistance, said cover being secured to the guides 1 and the upper camber 7 of the main airfoils 3.

' The auxiliary airfoils will have a normal position aneularly disposed with reference to the aerodynamlc chord plane of the main airfoils and at such a distance from the said main airfoils that the height of the Venturi slot 13 will producen. condition of maximum efficiency with a high value of lift.

In operating an airplane so equi ped, in the event of taking oli, landing or ying in rarefied air, as in high altitude flying, the auxiliary airfoils may be moved away from the upper cambers of the main airoils 3 by means of the torque tube 30 and its associated parts, to increase the height of the Venturi slot 13. This opening adjustment may be very small to produce increased values of lift with slight losses in eliciency. To operate at the maximum eihciency, as when cruising the airplane, the auxiliary airfoils are then adjusted to their normal position.

By means of my construction of the auxiliary airfoil, in combination with a standard sectioned main wing, the litt range of said main win is not appreciably changed.. ln other wor s, the maximum lift under my censtruction occurs at an angle of attack ei? about 20 degrees, therefore enabling the air plane to make a conventional three-point landing. -Heretofore, airplanes usingr auxf iliary aix-foils could not possibly make a con ventional three-point landing and still utilize the maximum lift of their wings, because their maximum lift occurs at great angles of attack; viz: 24 to 30 degrees. The fact that my wing arrangement gives maximum lift at approximately twenty degree angle of attack does not make the airplane unsafe due to burbling, which produces stalling, be-

cause experiments have shown that with my construction the litt decreases Gradually at the burbling stage, instead of abruptly.

. 1 claim:

l. In an airplane, a main airfoil, an auxiliary airfoil, said auxiliary airfoil having its nose spaced above and in advance of the nose of the main airfoil and being movable in a direction perpendicular to its aerodynamic chord plane, means for moving the auxiliary airfoil, and means for limiting the movement of the auxiliary airfol towards the main airfoil to always maintain an air passage therebetween.

2. In an airplane, a main airoil, an aux iliary airfoil, said auxiliary airi'oil having 1 n per Icam r and 'the aerodynamic chord' ular to its aerodynamic chord rits nose d' abvefthe intersection of the ane of the main airfoil. said auxiliary airil being movable in a direction perpendiclane means for moving the auxiliary airfo' and means for limiting the movement of the auin'liary airfoil ytowards themain airfoil to always maintain an air passage therebetween.

f 3. In an'airplane, a-main-.cambered airfoil, an auxiliary cambered airfoil havin a continuous upper' camber and an irregu ar lowercamber, said cambers being defined by the curvaturelof the leading upper camber of the-main airfoil, scid"auxiliary airfoil beingspaced above the main airfoil to form a. continuously open air passage therebetween, movable in a direction perpendicular to its aerodynamic chord plane to vary said air passage.

Il...A ln an airplane, a main cambered airfoil, an aum'liary cambered airfoil having a continuous upper camber and an irregular lower camber, said cambers being defined by the curvature of the leading upper cainber of the main aiioil, said auxiliary airfoil being movable in a direction perpendicular to its aerodynamic chrd plane and spaced above the main airfoil'to form a continuously open air passage therebetween, said auxiliary air- 'oii having its nose disposed above the intersection of the upper camber and the aerodyiiaiiicchord plane of the main airfoil.

. .ln an airplane, a main airfoil, an auxilieiy airfcil disposed above the intersection of the upper @amber and the aerodynamic chord plane of the main airioil to providea space therebetween, with the opening of ci the space less than the width of 'tlie opening at the front to produce a Venturi passage therebetween, means for moving said auxiliary airfoil in a direction perpendicuisr to its aerodynamic chord plane, and

c interposed' between the' main and ,auxiliary airfoilslimiting the movement or c auxiliary air'oil towards the main air' whereby to always maintain the Venturi passage. A

ln an airplane, a main airfoil, an auxilsirf'oil. continuously spaced from the n airfoil, means :roi moving the auxiliary lil in a direction lperpendicular to its all " aerodynamic chord plane, said means including s rotatable torque tube, an adjust-A able threaded screw connected to the auxiliary airfoil, a'rotatable sleeve in threaded engagement with the screw, a gearpn the sleeve and a gear on the torque tubeLsaid gears meshing to rotate the sleeve by a. rota- 'ticfoithe tube, and means for limiting the movement of the auxiliary airfoil towards the main airfoil to always maintain an air passage therebetween.

. The herein desb'ribed method of defining the upper and lower cambers of an auxilaprendes iaryairfoil'v which consists in' denin the upper and ower cambers of its airl'fo' section from a standard or pre-formed imain airfoil section by first movingthe vstandard section upwardly parallel to its aerodynamic chord and forwardly through equal distances, whereby a portion of the lower camber of the auxiliary section is dened bthe forward upper camber of the standar section; then moving the standard section forwardly along a continuation of its aerodynamic chord until the upper camber thereof intersects the said portion of the lowercamber of the auxiliarysection at or about the 'til the forward upper camber of the said section becomes tangent to the aforesaid lower camber ortion of the auxiliary. section, thereby de 'ning and completing the auxiliary section. l

8. The herein described method of delining the upper camber of an auxiliar -cambeied airfoil from a standard or preormed main airfoil section, which consists iii first moving the standard section upwardly parallel to its aerodynamic chord and forwardly through equal distances, whereb a portion of the lower caniber of the auxi iary airfoil section is defined by the forward upper cainber of the standard section, then moving the standard section forwardly along a continuation of its aerodynamic chord until the upper camber thereof intersects the said portion of the lower camber of the auxiliary section at or about the point of maximum ordinate of lsaid .upper camber.

9. ln an airplane, a main cambered airfoil, an auxiliary cambered airfoil spaced from the main airfoil to provide a continuously open air passage therebetween, said auxiliary airfoil having a continuous upper camber deico ics

iis 

